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  • Cell & Developmental Biology  (16)
  • 1930-1934  (11)
  • 1925-1929  (5)
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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 43 (1926), S. 81-103 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Paramecium trichium varies from 50 μ to 105 μ long with most individuals between 80 μ and 90 μ. The width varies from one-third to one-half the length. It is somewhat depressed dorsoventrally. The broad buccal groove extends from the anterior left border diagonally across the ventral surface to the mouth, which is usually slightly anterior to the middle and to the right side of the median line. The mouth leads into a relatively long cytopharynx containing an undulating membrane. The cytopyge is subterminal and the small caudal tuft of longer cilia is subapical. The plastic ectosarc contains numerous trichocysts. A contractile vacuole apparatus occurs near either end. Each is deeply located and stains more intensely than surrounding protoplasm. In life there appear to be two alternately contracting vacuoles with smaller ones adjacent. Contractions are from fifteen to twenty-five per minute. The macronucleus is medium in size and the single micronucleus is of the ‘caudatum’ type.Binary fission appears to be initiated by a metaphase-like condition of the micronucleus. This is followed by great enlargement and the eventual separation of the chromatin threads into two anaphase groups. The metaphase thus appears to precede the changes which correspond to a prophase in other cases. During division of the body, the two old contractile vacuoles persist as the posterior ones for the daughters, new anterior ones being developed.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 47 (1929), S. 37-87 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The vesicular nucleus of this amoeboflagellate is similar in structure in both phases of its life-cycle. It has a fairly large caryosome surrounded by a pericaryosomal area in which there are small oxyphilic pericaryosomal granules on a fine reticulum. On the inner surface of the definite caryotheca is a layer of epithecal chromatic granules.Nuclear division is similar in both amoeba and flagellate phases. During the prophase the nucleus enlarges, and the expanded caryosome becomes resolved into basophilic and oxyphilic components and assumes either an oblong, dumb-bell, or spindle shape. The pericaryosomal granules enlarge, shift about, and eventually become arranged in an equatorial band around the elongated caryosome. In the metaphase the equatorial plate of chromosomes appears after the inward migration of the pericaryosomal granules, accompanied by the formation of a definite intranuclear spindle, usually with polar masses, polar granules, and a centrodesmose. After the poleward migration of the daughter plates of chromosomes in the anaphase, the telophase constriction of the nuclear membrane produces two daughter nuclei with a portion of the spindle remaining outside. The epithecal layer of granules remains in place on the nuclear membrane during the entire process of mitosis. Plasmotomy normally follows mitosis, but may be delayed, giving rise to multinucleate individuals. In the flagellate the blepharoplast usually divides simultaneously with, but independently of, the nucleus. There are many divergences in the details of mitosis, but these are thought to be variations of one type of division rather than examples of different processes.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 47 (1929), S. 415-433 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The diploid number of twenty-six chromosomes was found in the mature parthenogenetic female-producing eggs and also in the somatic cells of the female embryos developing from such eggs. In the maturation stages of a few of these eggs the chromosomes were markedly larger than in the corresponding stages of the majority of the eggs. Whether this size difference of the chromosomes is correlated with male- and female-producing individuals has not been determined. The mature parthenogenetic male-producing eggs contain the haploid number of thirteen chromosomes, and this number was found also in the somatic cells of the young male embryos. The mature sexual eggs contain thirteen chromosomes.In spermatogenesis the secondary spermatocyte divisions are usually omitted and the secondary spermatocytes develop directly into the motile spermatozoa containing thirteen chromosomes. A few, however, of the secondary spermatocytes divide, forming spermatids containing fewer than thirteen chromosomes. These cells develop into the non-motile and rudimentary spermatozoa.The motile spermatozoa containing thirteen chromosomes unite with the parthenogenetic male-producing eggs containing thirteen chromosomes, thus producing the fertilized eggs with the diploid number of twenty-six chromosomes. These fertilized eggs develop into female-producing females which reproduce parthenogenetically.
    Additional Material: 5 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 55 (1933), S. 81-118 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The development of the interatrial septum and the relation of the sinus venosus and sino-atrial valves to the interatrial septum was followed in chick hearts ranging from 50 hours of incubation to the adult. The following singificant facts were established. The interatrial septum first appears at about 50 to 55 hours of incubation. It fuses with the endocardial cushions of the atrio-ventricular canal, typically in the last quarter of the fifth day. Secondary perforations appear in the septum at the time of closure of the interatrial foramen primum. These are retained until hatching, although they may persist in the adult heart. The sinus venosus, a sinus septum, and the sino-atrial valves are retained as definite structures in the adult fowl heart. The pulmonary vein and the left precava as they enter the heart form a prominent addition to the inter-atrial septum proper which I have designated as the pars cavo-pulmonalis. The pulmonary orifice in the left atrium is provided with an extensive flap-like valve. A prominent limbus of Vieussens is present in the right atrium. A well-developed median muscular arch overlies the interatrial septum and a pair of lateral muoscular arches extend over the atria. Their position would seem to be significant in the closing septal perforations during atrial systole.
    Additional Material: 14 Ill.
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  • 5
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Amoeba proteus was raised in a modified and diluted Ringer solution. When the pH of this culture medium became less than 6.0, the normal activities of the amoebae were interfered with; and when a still lower pH was attained, the amoebae died off. The same was true when the pH became greater than 8.0. At neutrality the activities were subnormal, very dark, and rounded. The rate of locomotion of amoebae raised in solutions with a pH less than 7.0 showed a maximum rate of locomotion at pH 6.6, which decreased as the pH changed in either direction, dropping to a very low rate at pH 7.0 and above and also below 6.0. For amoebae raised at a pH above 7.0 the rate was maximum at pH 7.6 and decreased as the pH changed in either direction; it was low at pH 7.0 and below and also above 8.0.On increasing the external osmotic pressure of the medium it was found that the effects caused varied somewhat with the hydrogen-ion concentration. Small increases in osmotic pressure decreased the rate from the normal at pH 6.0 and 8.0, increased it at pH 6.6 and 7.6, and did not affect it at pH 7.0. Osmotic pressures above that produced by M/20 lactose caused locomotion to cease in a short time at all pH values.
    Additional Material: 4 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 55 (1933), S. 193-205 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Tritrichomonas foetus (Riedmüller) which occurs in the genital tract of domestic cows and which appears to be associated with pathological conditions, including sterility and abortion, has been found in American cows and its morphology studied.The spindle-shaped body is 10 to 25 μ in length and bears three anterior flagella and a posterior flagellum which constitutes the marginal filament of the nearly full-length undulating membrane and continues posteriorly as a trailing flagellum. There is an accessory filament in the undulating membrane. The axostyle is of the thick, hyaline type and contains endoaxostylar granules in the capitulum and bears a chromatic ring at the point of emergence from the body. There is a well-developed costa under the undulating membrane and a simple type of parabasal body.In its morphology this species more nearly resembles such intestinal forms as T. augusta and T. muris than it does Trichomonas vaginalis of man, since the latter has four anterior flagella, a short undulating membrane without an accessory filament, no trailing flagellum, a different type of axostyle, and a parabasal filament along with its larger parabasal body.
    Additional Material: 2 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 56 (1934), S. 295-323 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The primordia of the thymus bodies in Necturus begin to form in 7-mm. embryos. These structures arise as clumps of entodermal cells on the posterior dorsal portion of the first four visceral pouches; the first or last pouch, being rudimentary, fails to form such a primordium. All except the first of these primordia lose their connection with their respective pouches in the 16-mm. stage and lie free in the surrounding connective tissue. The primordium on the first pouch begins to show degenerative changes during that stage, losing connection with its pouch in the 23-mm. stage, finally to disappear altogether in 30-mm. specimens.The three remaining bodies continue to grow, but the second and third outstrip the fourth in development and begin to form Hassall's corpuscles in 32- to 34-mm. stages. Sections of 30-mm. Necturi show a few of these corpuscles fairly well developed and containing a faintly staining secretion. The fourth body remains relatively small a long time, not showing the Hassallian cysts until the animal is 60 mm. long. By shifting of positions and increasing in size, the three bodies come to lie in proximity, one behind the other, to form the definitive thymus gland of the adult. The gland lies embedded in the heavy musculature on top of the head in front of the gills.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 55 (1933), S. 119-129 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The vascular channels and sinuses of this trematode contain three varieties of cells: eosinophilic granulocytes, primitive hemocytoblasts (‘amebocytes’), and modified hemocytoblasts. The latter suggest a specialized blood corpuscle, but represent apparently only a stage in the dissolution of intravascular hemocytoblasts. These ‘corpuscles’ have the form of flattened lenticular discs, approximately 12 μ in diameter. The eosinophils differentiate extravascularly from hemocytoblasts. The hemocytoblasts are in part free parenchymal cells, in part they arise from a bilaterally paired ‘lymphogenous organ’ or ‘blood island’ associated with the lateral vascular channels at the level where the ceca diverge from the esophagus.
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  • 9
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A chronological investigation of the histological condition of the right ovary of the domestic hen from embryos of nine days' incubation to adults of eighteen months was made. A rudiment of the right ovary is found at all times. Its composition is variable. Sixty-one per cent of the rudimentary ovaries contained medullary tissue only. Thirty-nine per cent had rudiments of cortex, in addition. The occurrence of cortical rudiments in embryonic stages is the probable basis of ovarian follicles found in the rudimentary right ovaries of adults. Primordial germ cells persist in the medullary tissue until three weeks after hatching. They subsequently appear to atrophy. The medullary cords persist through the entire period either as distended tubules or as solid cords of modified epithelial cells. Remnants of the right mesonephros persist as tubules and connect with the gonad by rete tubules. The mesonephric duct maintains a patent lumen.
    Additional Material: 18 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 50 (1930), S. 259-293 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A study of the development of the ear of the common dogfish from the 3.5-mm. stage to the adult, with a brief review of the literature and comparison with related forms.The study includes the following topics: First indications of vesicles. The beginning of specialization. The separation of component structures. The sensory epithelium. The structure of the adult ear, including a description of the sensory areas, the innervation, the lagena.The position of the future canals is first indicated in 15- to 20-mm. stages. The sacculus and utriculus were first noted in the 22-mm. stage. Complete separation of the canals, the sacculus, utriculus, the recessus utriculus, and the lagena has occurred by the time the 33-mm. stage is reached. Definite innervation of the ampullae is found at this stage.The article contains twenty-seven figures; eight of them are drawings made from wax reconstructions of various stages.
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